dsPIC30F Soft Modem Library Summary
Contents
The dsPIC30F Soft Modem Library is composed of ITU-T compliant algorithms for V.21, V.22, V.22bis, V.23, V.32 and V.32bis modem recommendations. Bell standard 103 is also included in this library. V.21, V.23 and Bell 103 are Frequency Shift Keying (FSK) modems. V.32, V.32bis and V.22bis are Quadrature Amplitude Modulated (QAM) modems. V.22 is a Quadrature Phase Shift Keyed (QPSK) modem. V.21, V.22, V.22bis, V.32 and V.32bis are all 2-wire, full-duplex modems. V.23 is full-duplex when it operates with a 75 bps backwards channel. V.22bis includes fallback to V.22, V.23 and V.21 standards. V.32bis optionally falls back to V.22bis, V.22, V.23 and V.21 standards.
The dsPIC30F Soft Modem Libraryis provided in two basic software packages: • V.22bis/V.22 offered free with full source code, includes: – V.22bis/V.22, V.23, V.21/Bell 103, V.42, DP and V.42 API, AT command set • V.32bis/V.32 offered in object code, includes: – V.32bis/V.32, V.22bis/V.22, V.23, V.21/Bell 103, V.42, DP and V.42 API, AT command set The library currently supports single channel data-pump implementations. Both libraries are supported with fallback data pump modulations down to V.21. Each data modem library is provided with a respective library archive containing all the data pump object code modules required to link to an application. UART and Data Converter Interface (DCI) for DAA/AFE I/O hardware component drivers are provided in assembly source code for linking with an application. ITU-T Recommendation V.42 is provided with each library. V.42 contains a High Level Data Link Control (HDLC) protocol referred to as Link Access Procedure for Modems (LAPM) and defines errorcorrecting protocols for modems. All data pump modulations are developed in ASM30 assembly code yielding optimal code size and execution time. The AT, V.42 and data pump APIs are based on MPLAB®C30 C Compiler language. Electronic documentation accompanies this library to help implement its functions. A comprehensive Soft Modem User’s Guide describes the required APIs for the AT, V.42 and data pump layers.
Typical Applications The dsPIC30F Soft Modem Library is well suited for small transaction orientated based applications such as, but not limited to: • POS terminals • Set top boxes • Drop boxes • Fire panels • Internet-enabled home security systems • Internet-connected power, gas and water meters • Internet-connected vending machines • Smart appliances • Industrial monitoring
Features and Performance of Data Modems Performance Algorithm(1) V.21/Bell 103(4) V.22/V.22bis V.23(4) V.32 V.32bis
V.42 DP + V.42 API AT Command Set
Data Rate (Kbps) 0.3 1.2 2.4 1.2 0.6 9.6 4.8 14.4 12 9.6 7.2 4.8
Half/Full Duplex Full Full
Data Mod. FSK PSK/QAM
Program Memory(2, 3) (Kbytes) 13 22
Data Memory(2, 3) (Kbytes) 1.0 1.7
Half
FSK
15
1.0
4.5
Full
QAM/TCM
31
3.2
12
Full
QAM/TCM
36
3.6
15
14 7 8
2.0 1.2 0.15
1.5 — —
— — —
MIPS 4.5 7
Notes: 1. Data pump modules, V.21, V.22, V.22bis, V.23, V.32, V.32bis and Bell 103 are implemented in Assembly language; V.42, data pump; AT command APIs are implemented in C language 2. The program/data memory usage for the V-series data pumps is NOT cumulative, due to the sharing of components internally 3. Memory size does not account for applications combining data pump, V.42 and AT commands (if required) 4. V.21/Bell 103 and V.23 data pumps do not require V.42 Technical Notes V.21 operates at 300 symbols per second, at mean frequencies of 1080 ±100 Hz and 1750 ±100 Hz. V.23 operates at mean frequencies of 1500 ±200 Hz for the 600 bps forward channel and 1700 ±400 Hz for the 1200 bps forward channel. The V.23 75 bps backwards channel has a mean frequency of 420 ±30 Hz. V.32 and V.32bis data modems operate at 2400 symbols per second on a carrier frequency of 1800 Hz, in both directions. Both V.32 and V.32bis implement Trellis Coding Modulation (TCM) for all data rates, except 4800 bps. V.32 includes uncoded 9600 bps.
www.microchip.com
DS70148B-11
